Adjustable return mechanism for a watch

ABSTRACT

A return mechanism for a watch having two hands comprises a pivoted lever acting on two heart cams, one for one watch hand and the other for another watch hand. The return lever is pivoted on a support by an eccentric pivot pin which is frictionally mounted on the support so that it can be rotated to change the pivot axis of the return lever relative to the two cams and thereby return both hands precisely to zero position.

. 22 'Filed:

21 Appl. No.: 210,958

United States Patent Ono I I I [541 ADJUSTABLE RETURN MECHANISM FOR A WATCH [72] Inventor: Tsuneyoshi Ono, Chino, Japan [73] Assignee: Xerorr Conn. I

' Dec. 22,1971

[30] I Foreign Application Priority Data Dec. 28, 1970 Japan ..'.....45/l32725.

[521 U.s. Cl SS/7 6 [51] Int. Cl..... ....G04t 7/04 [58] Field of Search", ..58/74-79 [56] References Cited UNITED STATES PATENTS 3,518,826 7/1970 Takashina um ..ss/74 Corporation,. Stamford,

51," 3,701,250 "[451 Oct. 31, 1972 FOREIGN PATENTS OR APPLICATIONS I {1,522,081 4/1968 France; ...58/74 PrimafyExaminef-Geotge H. Miller, Jr.

Attorney-Robert E. Burns et al.

v [57 I ABSTRACT A return mechanism for a watch having two hands comprises'a pivoted lever actingon" two heart cams, one for one watch hand and theother'for anotherwatch hand. The return lever is pivoted on a support by an eccentric pivot pin which is frictionally mounted on the support so that it can be rotated to change the pivot axis of the return lever relative to the two cams and thereby return both hands precisely to zero position; Y v

, 5 Clairns, 3 Drawing Figures- ADJUSTABLERETURNIVIECHANISMFORA WATCH The present invention relates toa retum'zmechanism for a stopvwatchor chronograph.

In a watch having two: return parts for example a However because of manufacturingyerrorcf the component parts, the return lever may. engage the two cams unequally so that when it .is stopped'by engagement with one cam there .is still a gap between the return lever and theother cam. This causes'indicating error in the zero positions of the hands. llnyorder tocorrect this, it has heretofore been. the practice to fileofi' the high cam so that the leverwill engageiboth equally in zero position. 'Howeverthe filing of thecamresults in a rough face sothat the .coefiicient' of friction is in-.

creased and the operation of the return mechanism is thereby impaired.- Moreover the angle of theflat face-of the cam engaged by the return lever may be; altered in the filing operation .so that, the'corresponding hand is not returned accurately to 'zero position. Correct filing .of the cam requires considerable skill and time thereby increasing the cost of manufacture of the watch.

It is an object of the present invention to, provide for convenient adjustment of the resetting mechanism of a stop watch or chronograph to correct for manufacturing errors "in a simple, quick and convenient manner The eccentric pivot pin 3 provides means forquickly and accurately adjusting the return lever 2 so as to engage both of the heart cams 5 and 6- equally and thereby bring the respective watch hands simultaneously and precisely to zero positionfIf, when the return lever 2 is fully engaged with the heart cam -5,,. there is still play between the lever and the flat faceofzthe heart cam 6, the eccentric pivot pin3isrotated so as to raise the pivot axis-as viewed in FIG. .1 and therebybring the face 2b of lever v2-into firm engagement with the flat faceof the cam 6. Conversely if there is a gap between the lever 2 and the heart-cam 5 when the leveris in .full engagement with theheart cam 6, the eccentric :pivot pin 3 is rotated so as to lower the pivot axis asviewed in FIG. 1. Moreover by reason of the different .anglesas which the faces 2a and 2b of the lever 2 are disposed it will be seen that lateral movement ofthe pivot va'xisof the return lever 2 as viewed in FIG. 1 will produce more change with respect to cam-=6 than with respect to cam 5. This provides a further means for adjustment of the engagement of the return lever'2 with, the heart iliary return lever -13.mounted on the support plate 4 by without increasing the numberof partsand thereby the r costof the watch.

t he object and advantages of the invention will be mately on a line 202 in FIG. l, and

FIG. 3 is a schematic plan view showing a modification. 1

In the embodiment illustrated in FIGS. land-2, the inner end of the stem of a manually operable return button 1 engages an arm of a returnlever 2 which is pivotally mounted by means of a pivot pin 3 on a support plate 4. The pivot pin 3 is a frictionally rotatable eccentric pin having a pivot shaft portion 3a fitting frictionally into a hole 4a in the support plate 4 and an eccentric portion 3b about which the return lever 2 operates and which accordingly defines the pivot axis of the lever. The eccentric pivot pin 3 is adjustably rotatable by means of a screw driver or other instruheldin the position to which it is rotated.

The return lever 2 has a flat face 2a engaging a heart 2b engaging a heart cam 6 for the minute hand. It will be seen that the heart camsSand 6 are spaced apart a pivot pin 14'. The auxiliary lever 13 has aflat face 13a engageable with a heart cam 5 for the second hand of the watch. The main return lever 12 has a portion 124; engageable with the auxiliary cam 13 to'actuate the heart cam 5 and a flat face 12b engageable with the heart cam 6. A return spring 17 acts onthe auxiliary lever 13 to returnto. lever 13, the main return lever 12 and the return button 1 to normal or rest position.

The return mechanism illustrated in FIG. v3 operates in the same manner as that of FIGS. 1 and 2 except that cam 5 for the second hand of the watch and a flat face from one another and thus at different distances from the Pi axis of the return lever 2. More er the cam the return lever 12, instead of acting directlyon the heart cam 5, acts through the auxiliary lever 13. As in the embodiments of FIGS. 1 and 2, 'the pivot axis of the main return lever 12 is adjustable both vertically'an'dlaterally as viewed in FIG. 3 by the eccentric. pivot pin 3 so that both heart cams 5 and 6 are fully engaged simultaneously so as to bring the corresponding hands precisely to zero position. a

Ifthe watch has more than two return parts as shown, the return mechanism in accordance with the present invention can be applied to any two of them so as to provide convenient and accurate adjustment.

I As will be seen from the foregoing vdescription, the eccentric pin serves both as an adjusting means and as the rotary axis of the return lever so that the number of parts of the mechanism is not increased by providing extra parts for adjustment. The adjustment of the mechanism can be effected quickly, easily and accurately by the singleoperation of rotating theeccentric pivot pin of the return lever. Moreoverthe adjustment is continuous rather than step-wise so that microadjustment is possible. If it is found that an over-adjustment has been made, this can be quickly and easily orrected merely by rotating the eccentric pivot pin of the return lever in the opposite direction. Such facile correction of over-adjustment was not possible with the prior art method of filing one of the heart cams. It will thus be vance in the art.

While preferred embodiments of the invention have been illustrated in the drawings and are herein particularly described, it will be understood that the invention is in no way restricted to these embodiments and'in particular the arrangement and location of the heart cams can be varied provided only that adjustment of the pivot axis of the return lever has a different effect with respect to one heart than with respect to another.

l. A return mechanism for a watch having two operating members, comprising a support, a manually operable return lever, means for pivotally mounting said return lever on said support, first cam means What I claim and desire to secure by Letters Patent to return both of said operating members precisely to starting position, said eccentricpin being frictionally held in adjusted position.

2. A return mechanism according to claim 1, in

which said return lever has two faces at different distances from said pivot pin respectively engaging said first and second cam means.

3. A return mechanism according to claim 2, in

which said faces are flat and are disposed at different angles relative to a line connecting each said face to the pivot axis of said return lever.

4. A return mechanism according to claim 1, in which an auxiliary return lever pivotally mounted on said support has a face engaging one of said cam means I and said return lever has a face engaging the other of said cam means and a portion engaging said auxiliary return lever.

5. A return mechanism according to claim 4, in which a return spring acts on said auxiliary return lever to return both said first-mentioned return lever and said auxiliary return lever to rest position.

a UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pa 3,701,250 Dated I October 31a, 1972 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

. In the heading of the printed patent item [73] after ""ASSI GNEE' oanoel "Xerox Corporation, Stamford, Conn." and insert -KABUSi-IiKI KAiSHA SUWA sEIKosHE, a oap an 'ese Company,

T'I'o kyo, Japan.-- I V I Signed and sealed this 12th day" of Feb riiary 1974.

(SEAL) Attest: v v I EDWARD M.FLETCHER,JR.

c. MARSHALL DANN Attestlng Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. :7 250 Dated O tOb r 1, 1972 lnventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading of the printed patent item [73] after "ASSIGNEE" cancel "Xerox Corporation, Stamford, Conn. and

insert -KABUSHIKI KAISHA SUWA SEIKOSHA, a Japanese Company,

Tokyo, Japan.

Signed and sealed this 12th day of February 1974.

(SEAL) Attest:

EDWARD M.FLETCHER,JR.

Attesting Officer LL DANN Commissioner of Patents "ORM PO-1050 (10-69) USCOMM-DC 60376-P69 a u.s. GOVERNMENT mm'rmc OFFICE: 1989 o38a-3:u, 

1. A return mechanism for a watch having two operating members, comprising a support, a manually operable return lever, means for pivotally mounting said return lever on said support, first cam means operable by said return lever for returning one operating member to starting position, second cam means operable by said return lever for returning another operating member to starting position, said first and second cam means being located at different distances from said pivot means, said pivot means comprising an eccentric pivot pin mounted on said support for rotation to change the pivot axis of said return lever relative to said cam means and thereby adjust said return lever to return both of said operating members precisely to starting position, said eccentric pin being frictionally held in adjusted position.
 2. A return mechanism according to claim 1, in which said return lever has two faces at different distances from said pivot pin respectively engaging said first and second cam means.
 3. A return mechanism according to claim 2, in which said faces are flat and are disposed at different angles relative to a line connecting each said face to the pivot axis of said return lever.
 4. A return mechanism according to claim 1, in which an auxiliary return lever pivotally mounted on said support has a face engaging one of said cam means and said return lever has a face engaging the other of said cam means and a portion engaging said auxiliary return lever.
 5. A return mechanism according to claim 4, in which a return spring acts on said auxiliary return lever to return both said first-mentioned return lever and said auxiliary return lever to rest position. 